Fix rules_rust on Linux/s390x. (#221)

Signed-off-by: Piotr Sikora <[email protected]>

Author: PiotrSikora

bazel/dependencies.bzl

@@ -15,11 +15,19 @@
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
 load("@proxy_wasm_cpp_host//bazel/cargo:crates.bzl", "proxy_wasm_cpp_host_fetch_remote_crates")
 load("@rules_python//python:pip.bzl", "pip_install")
-load("@rules_rust//rust:repositories.bzl", "rust_repositories")
+load("@rules_rust//rust:repositories.bzl", "rust_repositories", "rust_repository_set")
 
 def proxy_wasm_cpp_host_dependencies():
     protobuf_deps()
+
     rust_repositories()
+    rust_repository_set(
+        name = "rust_linux_s390x",
+        exec_triple = "s390x-unknown-linux-gnu",
+        extra_target_triples = ["wasm32-unknown-unknown", "wasm32-wasi"],
+        version = "1.57.0",
+    )
+
     proxy_wasm_cpp_host_fetch_remote_crates()
 
     pip_install(

bazel/repositories.bzl

@@ -92,6 +92,7 @@ def proxy_wasm_cpp_host_repositories():
         name = "rules_rust",
         sha256 = "8a2052e8ec707aa04a6b9e72bfc67fea44e915ecab1d2d0a4835ad51c2410c36",
         strip_prefix = "rules_rust-b16c26ba5faf1c58ebe94582afd20567ce676e6d",
+        # NOTE: Update Rust version for Linux/s390x in bazel/dependencies.bzl.
         url = "https://github.com/bazelbuild/rules_rust/archive/b16c26ba5faf1c58ebe94582afd20567ce676e6d.tar.gz",
     )
 

bazel/wasm.bzl

@@ -77,7 +77,7 @@ wasi_rust_binary_rule = rule(
     attrs = _wasm_attrs(wasi_rust_transition),
 )
 
-def wasm_rust_binary(name, tags = [], wasi = False, signing_key = [], **kwargs):
+def wasm_rust_binary(name, tags = [], wasi = False, signing_key = [], rustc_flags = [], **kwargs):
     wasm_name = "_wasm_" + name.replace(".", "_")
     kwargs.setdefault("visibility", ["//visibility:public"])
 
@@ -87,6 +87,11 @@ def wasm_rust_binary(name, tags = [], wasi = False, signing_key = [], **kwargs):
         crate_type = "cdylib",
         out_binary = True,
         tags = ["manual"],
+        # Rust doesn't distribute rust-lld for Linux/s390x.
+        rustc_flags = rustc_flags + select({
+            "//bazel:linux_s390x": ["-C", "linker=/usr/bin/lld"],
+            "//conditions:default": [],
+        }),
         **kwargs
     )